Adjustable double-ended directional lamp



Dec. 22, 1959 J, w, FULTON ETAL 2,918,644

ADJUSTABLE DOUBLE ENDED DIRECTIONAL LAMP Filed Oct. 31. 1956 lnven lrorsz John W FuL ton,

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uniformly distributed in a ,tud-inal axis of the lamp but with known lamps having a United States Patent O ADJUSTABLE DOUBLE-ENDED DIRECTIONAL LAMP John W. Fulton, Chardon, and Robert A. Kuebler, Cleveland Heights, Ohio, assignors to General Electric Company, a corporation of New York Application October 31, 1956, Serial No. 619,486 Claims. (Cl. 339-2) This invention relates to linear double ended electric lamps and to bipin bases for such lamps.

A type of base used in large numbers for straight elongated double-ended tubular fluorescent lamps having preheat type electrodes at each end and a pair of current leading-in wires extending from each end of its tubular glass envelope is one comprising a cylindrical metal shell cemented to an end of the envelope of the lamp and a spaced pair of parallel mutually insulated contact pins aflixed to the shell and connected to the lead-in wires.

Typical holders for lamps having at each end a base of this kind are disclosed and claimed in the Reissue Patent No. 21,545 of August 27, 1940, Marshaus, and Patent No. 2,292,043, Bryant, both of which patents are assigned to the assignee of this application.

In the holders disclosed and claimed in these patents the plane including the parts of the holder contacts engaged by the base contact pins when a lamp is rotated after insertion in the holders is transverse to a slot or groove along which the lamp contact pins are moved sideways when inserting the lamp into holders. These holders and other commercial types of holders may be mounted with the plane including the base pin-engaging parts of the holder contacts vertical or horizontal or at any angle therebetween in existing lighting installations.

This is immaterial when the light output of the lamp is plane transverse to the longidirectional characteristic, that is, having a non-circular light output distribution in such a plane, it is highly advantageous to be able to locate the lamp with the part thereof having the higher light output facing a desired direction.

Such known directional lamps are provided with a longitudinally and circumferentially extending reflecting surplane of the lamp contact pins for the purpose of obtaining a desired orientation of the envelope of a directional lamp mounted in such lampholders.

The principal object of the present invention is to provide such a directional lamp adapted for such envelope adjustments. Another object of the invention is to provide a base for such directional lamps by which the above purpose may be accomplished. Further objects and advantages of the invention will appear from the following detailed description of a species thereof.

2,913,644 Patented Dec. 22, 1959 The objects of the invention are attained by providing at each end of the linear envelope of such directional lamps a base comprising a cylindrical shell aflixed to the end of the lamp envelope coaxial with the envelope and a contact pin assembly including a pin-supporting member mounted for rotation on said shell with its axis of rotation coincident with the longitudinal axis of the shell. The spaced mutually insulated contact pins of the assembly are affixed to the supporting member and are positioned thereon symmetrically with and in a diametral plane including the axis of rotation of the assembly on the shell. Angular adjustments on its longitudinal axis of the linear envelope of a directional lamp having such bases may be made readily with the lamp mounted in lampholders to obtain a desired orientation of the envelope.

In the drawing accompanying and forming part of this specification an embodiment of the invention is illustrated, in which:

Fig.1 is a pictorial view of a directional lamp embodying the invention and a pair of holders for the lamp.

Fig. 2 is an enlarged end View of one of the lamp bases shown in Fig. 1 and as viewed from the envelope engaging end of the base.

Fig. 3 is a sectional view of the base shown in Fig. 2 taken along the line 3-3 of Fig. 2 and showing in section an end of the lamp envelope to which the base is cemented.

Fig. 4 is similar to Fig. 3 with the parts thereof rotated and the section of the base taken along the line of 44 of Fig. 2.

Fig. 5 is an enlarged end-on-view of the lamp shown in Fig. 1 and showing a preferred arrangement of the bases on the lamp envelope.

Referring to Fig. 1, there is shown an elongated tubular double-ended fluorescent lamp having a sealed vitreous light transmitting envelope 1 provided with bi-pin bases 2 and 3 of identical structure attached to the ends thereof. The envelope 1 transmits light passing through a window 4 defined by an internal reflecting coating 5, such as a coating of titanium dioxide, provided on a portion of its circumference. The common boundaries of the window 4 and the coating 5 are indicated by the lines 6 and 7 in Figs. 1 and 5 of the drawing. The reflecting coating 5 is interposed between the inner surface of the envelope 1 and the usual phosphor coating 8 extending around the entire inner circumference of the envelope 1 so that light produced by phosphor coating 8 is directed by the reflecting coating 5 through the window 4. The lamp thus has a directional characteristic in that it emits more light in the direction in which the window faces than in any other direction. The coating 5 is usually partially light transmitting.

In structural features other than the bases attached to the ends of the tubular-envelope 1 the lamp illustrated is similar to commercial fluorescent lamps having a nondirectional characteristic in that it is provided with an ionizable atmosphere including an inert starting gas, such as argon, at a low pressure and a small quantity of mercury indicated by the droplet 9. The lamp is provided at the ends of the envelope 1 with filamentary electrodes 10, one of which is shown in Figs. 1, 3 and 5, including a tungsten support and electron emissive oxide material on said support. The electrodes are of the hot starting type, that is, requiring either preheating current at starting or continuous heating current during starting and operation. A pair of flexible current leading-in wires 11 and 12 are sealed into the stems 13 at each end of the lamp envelope 1 for conducting preheat and operating current to the electrodes 10.

During operation of the lamp a low pressure mercury vapor discharge between the electrodes within the envelope 1 causes production of resonance radiation at 2537 Angstrom wave length which is converted by the phosphor coating 8 on the inside of the envelope into visible light.

The bi-pin bases 2 and 3 attached to the ends of the envelope 1 are also similar in structure to the bases used heretofore for non-directional fluorescent lamps in that each base comprises a cylindrical cup-shaped metal shell 14 adapted to be cemented at its ri-m portion to the reduced end portion of the envelope 1, as shown in Fig. 3, and a pair of spaced parallel insulated contact pins 15 and 16 projecting outward in a longitudinal direction from the ends of the based lamp for engagement with lampholder contacts. The pins 15 and 16 are symmetrically arranged with and are in a diametral plane including the longitudinal axis of the lamp envelope 1 which is usual in fluorescent lamps when the bases are properly mounted on the envelope ends.

The bases 2 and 3 in accordance with the present invention are different from prior bases of the bi-pin type in that the contact pins 15 and 16 of each base are mounted on a disk support 17 made up of two disks 18 and 18 of organic plastic electrically insulating material. The disk support 17 engages an integral circular web 19 provided on the base shell 14 in such manner as to allow relative rotary displacements'of the shell 14 and the contact pin assembly including the pins 15 and 16 and the disk support 17 of a completed base. The support 17 is secured to the web 19 of the base shell 14 by the pins 15 and 16 which are staked to the support 17 and clamp the disks 18 and 18 thereof against opposite sides of the Web 19 as shown in Figs. 2, 3 and 4 of the drawings.

The web 19 of the shell 14 is provided with two diametrically opposed arcuate' or kidney shaped slots 20 and 21 having their center of curvature coincident with the center of the circular web 19 and the support 17 is provided with protrusions 22 and 23 on the sides of disks 18 and 18' respectively, which engage the web 19. The protrusions 22 and 23 extend into and engage the sides of the slots 20 and 21 to center the disk support 17 on the web and also to limit the relative rotary movements of the contact pin assembly and the base shell.

The position of the window 4 of a lamp provided with bases 2 and 3 of the above structure mounted on the ends of its envelope 1, with the shell of each base cemented anti-turningly to the reduced diameter end portion of the envelope 1 in the usual manner, as shown in Fig.

3, and with the axis of relative rotation of the shell 14 and the contact pin assembly 15, 16 and 17 of each base coincident with the longitudinal axis of the envelope 1, may be changed while the lamp is mounted in lampholders, such as the holders 24 shown in Fig. l of the drawing, without changing the position of the contact pins in the holders by rotating the envelope 1 on its longitudinal axis. The higher light output side of the lamp thus may be faced in a desired direction.

The protrusions 22 and 23 on the disk support 17 and the slots 20 and 21 provided in the circular web 19 of the shell 14 not only serve to center the support on the web but also prevent twisting together of the leading-in wires 11 and 12 of the lamp, which would short-circuit the heating current to the electrodes, by limiting the relative rotary movements of the shell and the contact pin assembly.

Since the pins of a mounted lamp may be rotated 180 in the holders and the lamp may be turned end for end when mounting it in the holders, a relative rotary displacement of 90 between the shell 14 and the disk support 17 would be sufficient to allow angular adjustment of the envelope 1 of a based lamn effective for positioning the median plane of the window at any angle within the full circle of 360 around the longitudinal axis of the envelope 1. However, it is preferred to allow for angular adjustments of the envelope of greater magnitude, such as an adjustment of 110, to afford more positional flexibility.

This may be done without risk of twisting together the wires 11 and 12 by mounting the bases 2 and 3 on the ends of the envelope 1 in such position that, with the shell 14 and the disk 17 at the midpoint of rotation, the common diametral plane of the contact pins 15 and 16 and the common plane of the electrodes 10 and the wires 11 and 12 at each end of the envelope 1 coincide as shown in Fig. 5 in which the line AB indicates the position of these planes.

Thus, when the envelope 1 is rotated longitudinally an angular distance of 55 from the midpoint of rotation with the contact pins in a fixed position in a lampholder the protrusions 22 and 23 on the disk support 17 engage ends of the slots 20 and 21 and parts of the wires fastened to the pins are spaced an angular distance of 55 from the parts of the respective wires sealed into the stem 13 in one direction and are similarly spaced in the opposite direction of rotation of the envelope 1.

While such relative positioning of these lamp parts is preferred it is not essential that the common plane of the electrodes 10 and the lead-in wires 11 and 12 and the diametral plane of the contacts 15 and 16 coincide when the shell 14 and the disk 17 are at the midpoint of rotation. These planes may be at any angle with respect to each other which does not result in twisting of the wires 11 and 12 together when the shell and the disk are at their limits of relative rotation in either direction from their midpoint of rotation. This, of course, simplifies the manufacture of lamps equipped with such bases.

It has been found, however, that it is advantageous to correlate the position of the median plane of the window 4 and the diametral plane of the pins 15 and 16. For example, when the window 4 extends an angular distance of 140 around the circumference of the envelope 1, as shown at 6 and 7 in Fig. 5, it is preferred to correlate these planes in such manner that, with the shell 14 and the disk 17 at their midpoint of rotation these planes are,

at an angle of approximately 40 with respect to each other as illustrated in Fig. 5 in which the line C-D indicates the position of the median plane of the window 4. This angle is preferred because a desirable distribution of the directional light output of the lamp in each of the four quadrants of a lamp mounted in lampholders with the common diametral plane of the contact pins horizontal is obtainable when the total angular displacement of the envelope on its longitudinal axis with respect to the diametral plane of pins is as explained more fully later herein.

For convenience in mounting the bases 2 and 3 on the ends of envelope 1 with the diametral planes of the pins and the median plane of the window 4 in the desired relation, a detent 25, 26 (Figs. 4 and 5) to hold the shell 14 and the disk support 17 at their midpoint of rotation while mounting the bases on the envelope and an indicator 27 at right angles to the diametral plane AB of the pins 15 and 16 are provided. The detent is comprised of a pawl constituted by a dent 25 in the web 19 of the shell 14 and a series of notches 26 in the web engaging face of the disk 18'. The indicator 27 is in the form of a groove in the exposed face of the disk 18 at the peripheral portion of the disk 18.

The desired angular relation between the diametral plane AB of the pins and the median plane CD of the window may be established by off-setting the indicator 27 on each of the bases 2 and 3 an angular distance of 20 from one of the boundaries 6 and 7 of the window 4 when mounting the bases on the envelope. In Fig. 5 of the drawing the indicator 27 is shown so spaced angularly from the boundary 6.

With the bases 2 and 3 so mounted on the envelope 1 the lamp may be inserted in the spacedholders 24 shown in Fig. 1. In an actual installation the holders 24 are spaced apart a distance such that their inner faces sired direction.

are in contact with the end surfaces of the bases 2 and 3 when the lamp is mounted therebetween.

Lampholders 24 are of the wafer-type well known in.

the art for accommodating bi-pin fluorescent lamps and may be constructed in accordance with the re-issue Marshaus patent and the improvements of the Bryant patent mentioned above. Each lampholder comprises a housing 32 of suitable insulating plastic provided with an opening 33 of generally circular form in its front face which merges with a slot 34 extending from the opening to the outer edge of the housing. An insulating guide stud 35 projects forward substantially to the plane of the opening 33 and is provided with a groove 36 in alignment with the slot 34. Spring contact blades 37, 38 are mounted in spaced relation on opposite sides of the guide stud 35 for engagement with the contact pins the lamp.

In mounting the lamp, the contact pins on each of the bases 2 and 3 are moved upward in alignment through the slot 34 and the groove 36 until the innermost pin engages the wall of the opening 33; thereafter, the lamp is rotated 90 on its longitudinal axis to move the contact pins into engagement with the slightly V-shaped parts of the contact members 37, 38 located in a plane normal to the slot 34 and the groove 36. The indicator '27, being normal to the diametral plane of the pins 15 and 16 is useful also in mounting the lamp in the holders by indicating the position the pins in the holders. For example, with holders of the type shown in Fig. l, in which the pin engaging parts of the holder contacts are in a plane normal to the pin receiving slot and groove in the holder, the lampis rotated in the holders until the indicator 27 on each of the bases 2 and 3 coincides with the slot 34 in each of the holders or is in a position 180 from the slot depending upon the desired position of the window 4. In either position the indicator 27 shows that the pins 15 and 16 are properly engaged with the V-shaped parts of the holder contacts 37 and 38.

When inserting the lamp in its holders it is convenient to first rotate the pin assemblies on both ends of the lamp an angular distance of 55 from their midpoint of rotation in the same direction, which may be either clockwise or counter-clockwise, to overcome the hold ing force of the detent 25, 26 and to bring the protrusions 22, 23 against the ends of the slots 20, 21. The lamp is then moved transversely of its longitudinal axis upward into the holders and then rotated around its longitudinal axis as described above to bring the contact pins into engagement with the holder contacts. Preferably, the direction in which the lamp is rotated to seat it in the holders is opposite the direction in which the pin assemblies were rotated in preparing to mount the lamp. The protrusions are thus held at the same ends of the slots while rotating the lamp though this is not essential.

After the lamp has been seated in its holders in the manner described above, angular adjustments of the window 4 with respect to the diametral plane of the pins 15 and 16 may be made. For example, if the diametral plane of the pins of the mounted lamp is horizontal as shown in Fig. 5 the median plane C-D of the window will be either 5 or 15 outside a quadrant defined by the horizontal plane A-B and the vertical plane E-F including the longitudinal axis of the lamp envelope and through which quadrant the median plane C-D of the window 4 may be moved in facing the window in a deln Fig. 5 the extreme positions of the median plane CD of the window are indicated at CD and CD and the corresponding positions of the boundaries 6 and 7 of the window 4 are indicated at 6, 6" and 7, 7".

After the lamp has been seated in the holders the envelope may be rotated longitudinally 110 from its ex- .treme angular position with respect to the plane of pins 6 15 and 16 to pass the median plane of the window completely through the quadrant, when desired, or the angular rotation of the envelope may be stopped before reaching its limit of to position the median plane of the window within the quadrant, when desired.

The quadrant through which the median plane of the window may be moved by turning the envelope 1 of a mounted lamp on its longitudinal axis may be selected and may be any of the quadrants defined by the aforesaid planes AB, EF depending upon the position in which the lamp is inserted in the holders. The quadrant through which the median plane of the window is to be passed or within which it is to be adjusted may be selected by rotating the lamp longitudinally to turn the plane of the pins in the holders or by turning the lamp end for end bodily in the holders as pointed out above.

The holding force exerted by detent 25, 26 need be and preferably is just sufiicient to hold the shell and the disk support against relative rotation during mounting of the bases on the lamp envelope and sufiicient also to hold the envelope against rotation caused by vibration of a based lamp mounted in lampholders. In any event it is desirable that the holding force exerted by the ratchet be less than the holding force exerted by the holder contacts on the base pins of a mounted lamp to facilitate adjustment of the envelope and mounting and dismounting of the lamp in its holders. The torque then required to efiFect angular adjustment of the envelope is less than the torque required to turn the pins in the holders. The num ber of notches 26 may be increased, of course, three only being shown in the drawing for simplicity of illustration.

While a species of the invention has been shown in the drawing and described above, it will be understood, of course, that such showing and description is for illustrative purposes and that numerous changes in the form and details of the lamp and of the base may be made by those skilled in the art without departing from the invention as defined in the appended claims, for example, the window 4 may be made wider or narrower and the light transmitting characteristics of the reflecting coating 5 may be changed to obtain a desired light output distribution of the lamp. The luminescent coating 8 may be omitted in whole or in part and the envelope 1 made transmissive of the 2537 Angstroms wavelength germicidal radiation generated by the mercury vapor discharge in the lamp.

A species of base for an adjustable double-ended directional lamp comprising a single disc sup-porting the contact pins and a rivet means securing the disc to the webof the base shell for rotation around the longitudinal axis of the shell is disclosed and claimed in the copending application of Dale A. Grovemiller and Joe L. Elam, Serial No. 619,485 of even filing date herewith, now Patent No. 2,864,067 dated December 9, 1958, which application is assigned to the assignee of the present application. A base similar in structure to that of the copending application and comprising inter-engaged parts on the web of the shell and on the disc supporting the contact pins, which parts include a frangible pin and lock the disc and the shell in predetermined relative rotational positions for mounting the base on a lamp envelope, is disclosed and claimed in the copending application of Anton M. Krupp, Serial No. 679,631, filed August 22, 1957, which application is also assigned to the assignee of the present application.

What we claim as new and desire to secure by Letters Patent of the United States are:

1. A linear double-ended electric lamp having a directional light output in a plane transverse to its longitudinal axis and comprising an elongated generally tubular vitreous envelope having a pair of spaced flexible leading-in wires extending from each of its ends and a base mounted on each end of said envelope provided with a pair of mutually insulated spaced contact pins fastened to said wires and protruding outwardly for engagement with contact members of holders for said lamp, the pins on eachof light output of said lamp mounted in spaced lampholders are effected without moving the contact pins in the holders by angular displacements on its longitudinal axis of said lamp envelope with respect to the diametral plane of said pins.

2. A linear double-ended electric lamp having a directional light output in a plane transverse to its longitudinal axis and comprising an elongated generally tubular vitreous envelope having a longitudinally extending window and a pair of spaced flexible leading-in wires extending from each of its ends and a base mounted on each end of said envelope provided with a pair of mutually insulated spaced contact pins fastened to said wires and protruding outwardly for engagement with contact members of holders for said lamp, the pins on each of said bases being symmetrically mounted with respect to the longitudinal axis of said envelope and in a diametral plane, each of said bases comprising a cylindrical shell coaxial with said envelope and having a rim affixed anti-turningly to an end of said envelope and an integral circular web at the end thereof opposite said rim, and a pin assembly including said pins and a support therefor rotatably mounted on the web of said shell with its axis of rotation coincident with the axis of said shell and said envelope whereby changes in the direction of maximum light output of said lamp mounted in spaced lampholders are effected without moving the contact pins in the holders by angular displacements on its longitudinal axis of said lamp envelope with respect to the diametral plane of said pins.

3. A linear double-ended electric lamp having a directional light output in a plane transverse to its longitudinal axis and comp-rising an elongated generally tubular vitreous envelope having a longitudinally extending window defined by a reflecting coating on said envelope and a pair of spaced flexible leading-in wires extending from each of its ends and a base mounted on each end of said envelope provided with a pair of mutually insulated spaced contact pins fastened to said wires and protruding outwardly for engagement with contact members of holders for said lamp, the pins on each of said bases being symmetrically mounted with respect to the longitudinal axis of said envelope and in a diametral plane, each of said bases comprising a cylindrical shell coaxial with said envelope and having a rim aflixed anti-turningly to an end of said envelope and an integral circular 'web at the end thereof opposite said rim, and a pin assembly including said pins and a support therefor rotatably mounted on the web of said shell with its axis of rotation coincident with the axis of said shell and said envelope whereby changes in the direction of maximum light output of said lamp mounted in spaced lampholders are effected without moving the contact pins in the holders by angular displacements on its longitudinal axis of said lamp envelope with respect to the diametral plane of said pins.

4. A linear double-ended electric lamp having a directional light output in a plane transverse to its longitudinal ;axis and comprising an elongated generally tubular vitreous envelope having a pair of spaced flexible leading-in wires extending from each of its ends and a base mounted ,on each end of said envelope provided with a pair of mutually insulated spaced contact pins fastened to said wires and protruding outwardly for engagement with contact members of holders for said lamp, the pins on each of said bases being symmetrically mounted with respect to the longitudinal axis of said envelope and in a diametral plane, each of said bases comprising a cylindrical she coaxial with said envelope and having a rim afiixed antiturningly to an end of said envelope and an integral circular web at the end thereof opposite said rim, and a pin assembly including said pins and a support therefor rotatably mounted on the web of said shell with its axis of rotation coincident with the axis of said shell and said envelope whereby changes in the direction of maximum light output of said lamp mounted in spaced lampholders are effected without moving the contact pins in the holders by angular displacements on its longitudinal axis of said lamp envelope with respect to the diametral plane of said pins, the web of said shell and said assembly having interengaging parts limiting the relative rotational movements thereof to less than an angular distance which would result in twisting of said spaced leading-in wires together from predetermined relative positions of said pins and said wires.

5. A linear double-ended electric lamp having a directional light output in a plane transverse to its longitudinal axis and comprising an elongated generally tubular vitreous envelope having a pair of spaced flexible leading-in wires extending from each of its ends and a base mounted on each end of said envelope provided with a pair of mutually insulated spaced contact pins fastened to said wires and protruding outwardly for engagement with contact members of holders for said lamp, the pins on each of said bases being symmetrically mounted with respect to the longitudinal axis of said envelope and a diametral plane, each of said bases comprising a cylindrical shell coaxial with said envelope and having a rim affixed antiturningly to an end of said envelope and an integral circular web at the end thereof opposite said rim, and a pin assembly including said pins and a support therefor rotatably mounted on the web of said shell with its axis of rotation coincident with the axis of said shell and said envelope whereby changes in the direction of maximum light output of said lamp mounted in spaced lampholders are effected without moving the contact pins in the holders by angular displacements on its longitudinal axis of said lamp envelope with respect to the diametral plane of said pins, the web of said shell and said assembly having interengaging parts limiting the relative rotational movements thereof to less than an angular distance which would result in twisting of said spaced leading-in wires together from predetermined relative positions of said pins and said wires, the web of said shell and said assembly having also interengageable parts exerting a holding force of suflicient magnitude to prevent casual rotation of said lamp envelope with respect to said assembly.

6. A lamp base comprising a cylindrical shell having a rim for attachment anti'turningly to an end of a lamp envelope and an integral circular web at the end thereof opposite said rim, said base comprising also a contact pin assembly including a pair of mutually insulated contact pins and a pin support holding said pins in parallel positions, said assembly being rotatably mounted on the web of said shell with its axis of rotation coincident with the longitudinal axis of said shell and with said pins symmetrical with the axis of rotation of said assembly and in a diametrical plane of said shell, said pins extending outwardly of said base in the direction away from the said shell rim for engagement with socket contacts.

7. A lamp base comprising a cylindrical shell having a rim for attachment anti-turningly to an end of a lamp envelope and an integral circular Web at the end thereof opposite said rim, said base comprising also a contact pin assembly rotatably mounted on said web with its axis of rotation coincident with the longitudinal axis of said shell, said assembly comprising a pair of mutually insulated contact pins and a support engaging said web and holding said pins in spaced parallel positions symmetrical with the axis of rotation of said assembly and in :1 diametral plane of said shell, said pins extending outwardly of said base in the direction away from the said shell rim for engagement with socket contacts, said support having an indicator thereon olisct from and normal to the diametral plane of said pins.

8. A lamp base comprising a cylindrical shell having a rim for attachment anti-turningly to an end of a lamp envelope and an integral circular web at the end of said shell opposite said rim, said web having a pair of opposed arcuate slots therein having a center of curvature coincident with the center of said web, said base comprising also a contact pin assembly rotatably mounted on said web with its axis of rotation coincident with the longitudinal axis of said shell, sai'd assembly comprising a pair of mutually insulated contact pins and a disk-shaped support engaging said web and holding said pins in spaced parallel positions symmetrical with the axis of rotation of said assembly and in a diametral plane of said shell, said pins extending outwardly of said base shell and in the direction away from the said shell rim for engagement with socket contacts, said disk support having integral parts engaging the sides of the slots in said web to limit the relative rotation of said shell and said assembly.

9. A lamp base comprising a cylindrical shell having a rim for attachment anti-turningly to an end of a lamp envelope and an integral circular web at the end of said shell opposite said rim, said base comprising also a contact pin assembly rotatably mounted on said web with its axis of rotation coincident with its longitudinal axis of said shell, said assembly comprising a pair of mutually insulated contact pins and a disk-shaped support engaging said web and holding said pins in spaced parallel positions symmetrical with the axis of rotation of said assembly and in a diametral plane of said shell, said pins extending outwardly of said base in the direction away from the said shell rim for engagement with socket contacts, said web and said support having interengageable parts constituting a detent exerting a holding force of sufficient strength to prevent casual relative rotation of said shell and said assembly.

10. A lamp base comprising a cylindrical shell having a rim for attachment anti-turningly to an end of a lamp envelope and an integral circular Web at the end of said shell opposite said rim, said web having a pair of opposed arcuate slots therein having a center of curvature coincident with the center of said web, said base comprising also a contact pin assembly rotatably mounted on said web with its axis of rotation coincident with the longitudinal axis of said shell, said assembly comprising a pair of mutually insulated contact pins and a disk-shaped support engaging said web and holding said pins in spaced parallel positions symmetrical with the axis of rotation of said assembly and in a diametral plane of said shell, said pins extending outwardly of said base in the direction away from the said shell rim for engagement with socket contacts, said disk support comprising two insulating disks clamped against opposite sides of said web by said pins, said disks having integral parts engaging the sides of said slots to limit the relative rotation of said shell and said assembly, said web having a protrusion thereon and one of said disks having an arcuately arranged series of slots in the web engaging face thereof and engageable with the protrusion on said web, said protrusions and said slots constituting a detent exerting a holding force of sufiicient strength to prevent casual relative rotation of said shell and said assembly.

References Cited in the file of this patent UNITED STATES PATENTS 1,557,870 Pachman Oct. 10, 1925 1,817,004 Hubbell Aug. 4, 1931 2,235,656 Thai Mar. 18, 1941 2,386,190 Betts Oct. 9, 1945 2,749,528 Albrecht June 5, 1956 

